Super tweeter for FullRange Driver


I have a pair of Audio Nirvana 15in Alinco Classics that I just got done getting into cabinets. After some listening impressions, I've realized I cant live with the high frequency response these things put out by themselves. They only go to about 15k hz. and it's made music lose its sparkle and sense of space and spacial cues. I was thinking of buying a pair of Fostek T90As and pointing them at the ceiling for a more even dispersion and better integration with the Audio Nirvana driver. My main question is what  capacitor volume would you suggest? Where in the frequency response would you crossover to the tweeter? Would wiring the 8ohm tweeter and the 8ohm Audio Nirvana in parallel make me need to change my amp(Audio Note Kit 1 300b Set) from 8ohm to 4ohms? Any other brands of tweeters recommended for a fullrange driver that is around 96bd efficent? Sorry for all the questions, incredibly new to trying to implement crossovers with full rangers. If this sounds like a bad idea. Please speak up. 
akwilson501
Assuming that you are correct and your current 15 is 96db, as long as that 96db is based on 2.83v @ 1 meter, you will need around a 10db pad on the Fostex.  The Fostex impedance curve shows that from 10k to 15k,  this tweeter runs nearly a flat 8 ohm,  so the tweeter pad is fairly simple.... For an Lpad,  you'll need a series resistor of 5.47 and a parallel behind that of 3.7.  Then for 6db crossover slope,  I would recommend several caps on hand between 1.3mfd and 2.0mfd and experiment with which blends best.  
I hope this helps, 
Tim 
 
Hey everyone, thanks for the help, the community has came together wonderfully for me as usual. I am just getting around to adding the Fostek supertweeters to the Audio Nirvana 15in. I ended up going with a .33uf capacitor with an lpad to attenuate the volume of the tweeter. It pairs up wonderfully with the driver and does exactly what I wanted it to. Really opened up the sound stage and added extra detail to everything. Music is much smoother and bass seems more realistic as well. Everything just flows better now. Couldnt recommend more. I will be saving up for some better tweeters at somepoint, for now I'm satisfied. 
Hi @akwilson501 ,

What kind of capacitor do you use?
The capacitor quality and jumper wire quality is very import too.
I prefer paper in oil capacitors for smother sound.

Regards,
Alex.